Here's a little K2 script I wrote to help "randomize" playing the timpani so that rolls sound more human.

-- Bob

"Timpani Left Right" script for GPO "Timpani KS.nki"

This script will take any left hand note and alternate
with the right hand as well as adjust the delay, 
velocity and sample offset by the user selected amounts.

Note: offset (sample_offset) only works when instrument
source is "sampler", not DFD!

on init
  {Variable to keep track if the next note is played with the left or right hand}
  declare $left:=1

  {Define knob so that we can set random delay offset}
  declare ui_knob $delay(0,100000,1000000)

  {Define knob so that we can set the random velocity offset}
  declare ui_knob $velocity(0,32,1)

  {Define knob so that we can set the play_note sample offset}
  declare ui_knob $offset(0,1000000,1000000)

  {Other variable(s)}
  declare $new_delay
  declare $new_velocity

  {Make knob values persistent}

  {Clear error message}
end on

on note 
  {Only process for notes that are in the left hand}
  if ($EVENT_NOTE>=36 and $EVENT_NOTE<=58)
    {Ignore the original note event}

    {Add initial randomn delay}
    if ($new_delay>0)
    end if
    {Start with the current event velocity}
    {Get a valid random velocity value if user selected a non-zero velocity}
    if ($velocity>0)
      if ($new_velocity<0)
      end if
      if ($new_velocity>127)
      end if
    end if    

    {Do we play the left or right hand?}
    if ($left=1)
      {Left hand, play note as-is}
      {Set flag so that next note plays with right hand}
      {Right hand, play note two octaves higher}
      {Set flag so that next note plays with left hand}
    end if
  end if
end on